1. Field of the Invention
This invention relates generally to an article capable of taking up fluid and/or particulate materials, and more specifically to an absorbent casingless article that may be used to take up and contain fluids and/or particulates.
2. Description of the Related Art
Absorbent socks formed of polyester and containing either cellulose in a free-flowing particulate form or containing particles of magnesium aluminosilicate or other particulate materials have been used to absorb and contain oils and non-aggressive fluids (e.g., the absorbent articles commercially available under the trademark PIG.RTM. and PIG.RTM.mat, from New Pig Corporation, Tipton, Pa.). Although such absorbent socks provide a contained, efficient way of absorbing hydraulic fluids, PCB's, and other substances to be cleaned from an environment, they also contain particulate inner material that may cause a problem of excessive dust and require use of a dust mask if a spillage from the sock occurs. In addition, such sorptive articles are limited in utility to fluids, and have little or no ability to pick up and retain solid particulates.
Other prior measures for absorbing leaked or spilled fluids have utilized clay, towels, buckets or cans. The problem with each of these methods relates to the difficulty and/or the expense of handling the oil-containing material or the container. Substances such as clay also have a lower absorbency than the materials used in the commercial PIG.RTM. and PIG.RTM.mat products.
It is well known that many fibrous or fabric substances absorb liquids to some extent. Such substances as cotton fiber and natural cellulose products absorb liquid more efficiently than many man-made fibers, e.g., melt-blown fibers, which cannot absorb water at all, but rather must rely on their capillary reaction to liquids. Thus, such synthetic fibrous yarns must be sufficiently porous to permit the moisture to diffuse between the fibers and be held between the fibers in a cleaning manner. These synthetic fibers, however, are often preferred for many other uses because of their strength, their high wearability and their limited shrinkage.
Desirable characteristics of fibrous webs or fibrous structures in enhancing fluid absorption include: high durability and resistance to abrasion; high absorption characteristics such as are shown by soft, loosely twisted yarns; ready dryability; fast drying; easy wringability; high wet tensile strength; and the ability to withstand repeated laundering without shrinking significantly.
In respect of particulate solids pick-up, retention, and release, a variety of fibrous or fabric-based materials are employed. Fibrous webs or fibrous structures used for such purpose should have the ability to achieve rapid pick-up of solids and release thereof upon shaking or liquid (water) immersion, and should also be resistant to charge effects such as may result in minimal particulate solids pick-up and/or retention efficiency.
U.S. Pat. No. 4,717,616, issued Jan. 5, 1988, to Harmon, discloses a mop head fabric construction that comprises a plurality of substantially parallel, abutting strands of textile material such as cords of twisted strands or yarns. Absorption in this product is accomplished through the use of capillary action exhibited by the very finely divided fibrous structures which possess a low fluid pick-up and retention capacity per unit volume, thereby physically limiting the amount of fluids that can be absorbed. These fibrous structures are limited in absorption capacity because of their large surface area per unit volume retained, and the wringability and dryability of these fibers.
U.S. Pat. No. 4,995,133, issued Feb. 26, 1991, to Newell, discloses a mop head comprising a plurality of web elements having involutions therein. The involutions may be formed by treatment conditions comprising successive tensioning/detensioning, compression, differential stressing of stretching, twisting, or combination of these or other conditions or treatments imparting involutions to the web elements. In one aspect, the web elements are formed of a non-woven material comprising a cellulose and synthetic fiber blend. The mop head utilizes the discovery that interstitially capacitive regions may be employed to contain liquids and/or fluids or mixtures of fluids and particulates within a three-dimensional framework, e.g., fabric structure, which is capable of retaining the fluids by surface tension forces and capacitance of the structure of the fabric. These capacitive interstitial regions of the sorptive structures of the invention of U.S. Pat. No. 4,995,133 also are desirable in that they release fluids and/or solid particulates more easily than conventional absorptive materials due mainly to the small structural surface area required to contain a droplet of liquid or fluid and/or solid particle in the fabric or sorptive structure of the invention.
It would be a significant advance in the art of sorptive articles to provide a sorptive article having increased sorptive efficiency, providing easy fluid and/or particulate solid take-up, retention, and release and which may be used and reused without the need for an outer skin/container to maintain the integrity of the sorptive article.